Trump adopted a bellicose stance towards Tehran long before he became president. But he was never comfortable with an indefinite stay in Syria yoked to Iran. The officials said that Trump was willing to tolerate fighting ISIS, but was already uncomfortable with the duration of the war for that purpose. In the spring, he told audiences that he was willing to pull out of Syria “very soon,” something his senior advisers had to expend political capital to reverse.

Yet in September, Bolton—known as one of Washington’s most hawkish foreign policy hands, especially towards Iran—effectively reshaped the war, with a new goal. “We’re not going to leave as long as Iranian troops are outside Iranian borders and that includes Iranian proxies and militias,” he told reporters during the United Nations General Assembly.

Some leading Pentagon officials were uncomfortable with Bolton’s anti-Iran goals in Syria. Days after Bolton’s statement, senior Pentagon officials signaled to Congress that they weren’t on board. “In Syria, our role is to defeat ISIS. That’s it,” Brig. Gen. Scott Benedict, an officer on the Joint Staff, testified to the House Armed Services Committee.